This invention relates to dental hand tool holders or handpieces in general and has specific reference to means for preventing the ingress of water into the head of a contra-angle in which the tool clamping chuck is rotatably mounted and driven, the head end adjacent the tool being closed by a wall formed with a hole permitting the passage of said tool.
When a drill cuts a cavity in a tooth, the working end of the tool is sprinkled by directing an air and water mist, or only water, thereagainst. In this case the water spray hits very irregular surfaces and rebounds in all directions, including along the drill shank, from which it is liable to penetrate into the contra-angle head.